I find it hilarious that you go on and on about the 480, which is a card that was to replace the 380, neither of which were to compete with the 970, yet the 480 does compete with not only the 970 but the 980.
Reports that stock of the 4gb has already run in out some places? And AMD not making more.
So you've got a £230 (ish) replacement for the 380. That's £50 more, and basically that's a 390 in a nutshell.
Blame Brexit if you like, but that's the reality now the 4gb cards are gone.